Generally, in a braking device of an automobile, a brake pad is pressed against a braking surface on both sides of a brake disk rotor attached to a wheel using hydraulic pressure, thereby slowing or stopping a movement of the brake disk rotor (wheel). A driver operating a brake pedal performs this operation. Therefore, the braking surface is required to be processed (by grinding or cutting) such that the brake disk rotor does not shake from a shaft center when the brake pad is pressed against the braking surface of the brake disk rotor.
For example, as shown in FIG. 1, a brake disk braking surface processing device 1 rotates a hub unit 3 on which a brake disk 2 is mounted. Tools 6 are pressed against braking surfaces 4 and 5 of the brake disk 2. As a result, processing such as grinding and cutting are performed. A similar brake disk braking surface processing device is disclosed in Japanese Patent Laid-open Publication No. 2002-210639.    Patent Document 1: Japanese Patent Laid-open Publication No. 2002-210639